Relay Settings & Commissioning
Protective relay settings calculation, programming file generation, field commissioning support, and PRC compliance documentation.
What are Relay Settings?
Relay settings are the numerical parameters programmed into protective devices that determine how they detect, measure, and respond to electrical faults. Settings development translates coordination study results and protection philosophy into device-specific configurations ensuring reliable, selective fault clearing.
Proper settings balance sensitivity (detecting all faults requiring protection) with security (avoiding unnecessary operations). Settings must account for CT/PT ratios, fault current levels, coordination requirements, and device-specific capabilities and limitations.
This work is essential for new installations, equipment replacements, generator interconnection, and NERC compliance. It supports PRC-005 maintenance documentation and PRC-027 performance requirements.
When This Study Is Required
New Relay Installations
Protection system design and commissioning
Relay Replacements or Upgrades
Modernization and technology changes
Settings Changes or Optimization
System modifications or coordination improvements
NERC Compliance Documentation
PRC-005, PRC-023, PRC-025, PRC-027 support
What eGridSync Delivers
Relay settings calculations (overcurrent, distance, voltage, frequency, etc.)
Settings tables with CT/PT ratios and primary/secondary values
Device-specific programming files (where applicable)
Settings rationale and technical justification
Coordination verification and margin documentation
As-left settings documentation
Field commissioning support (optional)
PRC compliance support documentation
Settings change management procedures (if required)
Inputs Required (Data Request Checklist)
| Item | Examples | Why Required |
|---|---|---|
| Relay make & model | SEL-351, GE D60, Schweitzer SEL-421 | Device capabilities and format |
| Coordination study results | TCC plots, settings recommendations | Basis for settings development |
| CT/PT ratios | Current and voltage transformer ratios | Primary to secondary conversion |
| Protection philosophy | Zones, backup, special requirements | Design requirements |
| System parameters | Voltages, impedances, load levels | Settings calculations |
| Existing settings (if applicable) | Current relay settings files | Baseline and validation |
Common Protection Functions
Overcurrent (50/51)
Instantaneous and time-delayed phase and ground protection
Distance (21/21G)
Zone-based impedance protection for transmission lines
Voltage/Frequency (27/59/81)
Under/over voltage and frequency protection
Differential (87)
High-speed bus, transformer, or generator protection
Common Settings Issues
Incorrect CT/PT Ratios
Settings not accounting for transformer ratios causing misoperation
Sensitivity Too High or Too Low
Either missing faults or causing nuisance trips
Undocumented Changes
Field modifications not reflected in records
Incompatible with Device Capabilities
Attempting settings that exceed relay limitations
Frequently Asked Questions
What are relay settings?
Numerical values that define how protective devices detect and respond to faults.
Do you provide settings files?
Yes—relay programming files compatible with device models.
Can you support commissioning?
Yes—settings verification and field testing support.
What manufacturers do you support?
SEL, GE, Siemens, ABB, Schweitzer, and others.
How does this relate to PRC-005?
Settings documentation supports maintenance and performance verification requirements.
Can you review existing settings?
Yes—verification against current system conditions and standards.
What if coordination requires changes?
We iterate settings to achieve selectivity within device capabilities.
Do you provide training?
We can recommend training providers; our focus is settings development.
What deliverables do you provide?
Settings tables, programming files, rationale documentation, and commissioning support.
How long does this take?
Typically 2-3 weeks after coordination study completion.
Ready for Relay Settings Development?
Contact eGridSync for relay settings calculations and commissioning support.